I was wondering if I'm doing something wrong or if this is not possible. I couldn't find another post on it, but when I add two different Immortal squads both with there own Juno A1, I can make them share one Neptune drop-ship according to the rules. But I cant seem to get this working on the list builder. It marks it as wrong when I only add a Neptune to one of the two squads.

The way to get the program to accept this as a legal configuration is to set one squad's transport option to "Neptune + 2x Juno A1" (or 2x A2, or A1+A2), and then right click the title bar of the other squad and select the option to link it to the first.

It'll change the display to show a little chain icon joining the borders of the two squads, and stop flagging it as an invalid transport option on the first one.